The present invention provides rapamycin derivatives and their use in the treatment of neurological disorders.
Ischemic stroke, which accounts for 83% of all stroke cases (the remaining 17% are of the hemorrhagic-type) occurs in approximately 700,000 Americans each year, which equates to roughly 1 stroke every 45 seconds. Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls, called atherosclerosis. These fatty deposits can cause two types of obstruction: 1) cerebral thrombosis, which refers to a thrombus (blood clot) that develops at the clogged part of the vessel and 2) cerebral embolism, which refers generally to a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brain's blood vessels until it reaches vessels too small to let it pass. Current therapies to treat ischemic stroke are limited. To date, the only approved drug for ischemic stroke is recombinant tissue plasminogen activator (rt-PA). rt-PA, which acts as a thrombolytic, has a limited therapeutic window of opportunity (3 hours), therefore allowing only 1-2% of all stroke patients to receive treatment. There are no marketed neuroprotectants agents for ischemic stroke.
Parkinson's disease (PD) is a neurodegenerative disease that is neuropathologically characterized by the selective degeneration of dopaminergic (DAergic) neurons of the substantia nigra. PD is a progressive disease with a mean age at onset of 55, although 15% of patients are diagnosed before the age of 50. It is estimated that 1.5 million Americans have PD. Some of the classical signs of PD are resting tremor on one side of the body, generalized slowness of movement (bradykinesia), stiffness of limbs (rigidity), gait or balance problems (postural dysfunction). Current PD medications treat symptoms, whereas none prevent or retard DAergic neuron degeneration.
Given their clinical importance, prototypical molecules that clearly exhibit both neuroprotective and/or neuroregenerative activities have been highly sought after. Neurotrophins are a family of proteins that have extraordinary therapeutic properties in pre-clinical models of neurodegeneration. Although experimentally promising, clinical development of neurotrophins was met with severe obstacles and setbacks, such as the inability to deliver these large proteins to target population of neurons, instability of the proteins, and non-specific activity.
What is needed in the art are further compounds useful in treating neurological disorders.